Crash fixes, reorg handling, and sync performance improvements

- Fix FFI panics with catch_unwind and safe CString construction
- Handle poisoned mutex/RwLock after prior panics instead of crashing
- Fix empty block list panics in clear_blocks and invalidate_block
- Reuse Tokio runtime across block fetch batches to reduce overhead
- Add fetch_blocks_with_runtime for caller-managed runtime lifecycle
- Update branding, dependencies, and checkpoints for DragonX

lib/src/grpcconnector.rs

@@ -155,15 +155,12 @@ where F : Fn(&[u8], u64) {
 
 pub fn fetch_blocks<F : 'static + std::marker::Send>(uri: &http::Uri, start_height: u64, end_height: u64, no_cert: bool, pool: ThreadPool, c: F) -> Result<(), String>
     where F : Fn(&[u8], u64) {
+    let mut rt = tokio::runtime::Runtime::new().map_err(|e| format!("Error creating runtime {:?}", e))?;
+    fetch_blocks_with_runtime(&mut rt, uri, start_height, end_height, no_cert, pool, c)
+}
 
-    let mut rt = match tokio::runtime::Runtime::new() {
-        Ok(r) => r,
-        Err(e) => {
-            let es = format!("Error creating runtime {:?}", e);
-            error!("{}", es);
-            return Err(es);
-        }
-    };
+pub fn fetch_blocks_with_runtime<F : 'static + std::marker::Send>(rt: &mut tokio::runtime::Runtime, uri: &http::Uri, start_height: u64, end_height: u64, no_cert: bool, pool: ThreadPool, c: F) -> Result<(), String>
+    where F : Fn(&[u8], u64) {
 
     match rt.block_on(get_block_range(uri, start_height, end_height, no_cert, pool, c)) {
         Ok(o) => Ok(o),

lib/src/lightclient.rs

@@ -1323,6 +1323,10 @@ pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
         // Create a new threadpool (upto 8, atleast 2 threads) to scan with
         let pool = ThreadPool::new(max(2, min(8, num_cpus::get())));
 
+        // Create a single Tokio runtime for all block fetches to avoid per-batch overhead
+        let mut rt = tokio::runtime::Runtime::new()
+            .map_err(|e| format!("Error creating runtime: {:?}", e))?;
+
         // Fetch CompactBlocks in increments
         let mut pass = 0;
         loop {
@@ -1359,7 +1363,7 @@ pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
             let last_invalid_height = Arc::new(AtomicI32::new(0));
             let last_invalid_height_inner = last_invalid_height.clone();
             let tpool = pool.clone();
-            fetch_blocks(&self.get_server_uri(), start_height, end_height, self.config.no_cert_verification, pool.clone(),
+            fetch_blocks_with_runtime(&mut rt, &self.get_server_uri(), start_height, end_height, self.config.no_cert_verification, pool.clone(),
                 move |encoded_block: &[u8], height: u64| {
                     // Process the block only if there were no previous errors
                     if last_invalid_height_inner.load(Ordering::SeqCst) > 0 {

lib/src/lightwallet.rs

@@ -746,14 +746,29 @@ impl LightWallet {
     /// After this, the wallet's initial state will need to be set
     /// and the wallet will need to be rescanned
     pub fn clear_blocks(&self) {
-        self.blocks.write().unwrap().clear();
-        self.txs.write().unwrap().clear();
-        self.mempool_txs.write().unwrap().clear();
-        self.incoming_mempool_txs.write().unwrap().clear();
+        match self.blocks.write() {
+            Ok(mut b) => b.clear(),
+            Err(p) => p.into_inner().clear(),
+        };
+        match self.txs.write() {
+            Ok(mut t) => t.clear(),
+            Err(p) => p.into_inner().clear(),
+        };
+        match self.mempool_txs.write() {
+            Ok(mut m) => m.clear(),
+            Err(p) => p.into_inner().clear(),
+        };
+        match self.incoming_mempool_txs.write() {
+            Ok(mut m) => m.clear(),
+            Err(p) => p.into_inner().clear(),
+        };
     }
 
     pub fn set_initial_block(&self, height: i32, hash: &str, sapling_tree: &str) -> bool {
-        let mut blocks = self.blocks.write().unwrap();
+        let mut blocks = match self.blocks.write() {
+            Ok(b) => b,
+            Err(p) => p.into_inner(),
+        };
         if !blocks.is_empty() {
             return false;
         }
@@ -1677,9 +1692,15 @@ pub fn scan_full_mempool_tx(&self, tx: &Transaction, height: i32, _datetime: u64
 
         // First remove the blocks
         { 
-            let mut blks = self.blocks.write().unwrap();
+            let mut blks = match self.blocks.write() {
+                Ok(b) => b,
+                Err(p) => p.into_inner(),
+            };
             
-            while blks.last().unwrap().height >= at_height {
+            while let Some(last) = blks.last() {
+                if last.height < at_height {
+                    break;
+                }
                 blks.pop();
                 num_invalidated += 1;
             }
@@ -1687,7 +1708,10 @@ pub fn scan_full_mempool_tx(&self, tx: &Transaction, height: i32, _datetime: u64
 
         // Next, remove entire transactions
         {
-            let mut txs = self.txs.write().unwrap();
+            let mut txs = match self.txs.write() {
+                Ok(t) => t,
+                Err(p) => p.into_inner(),
+            };
             let txids_to_remove = txs.values()
                 .filter_map(|wtx| if wtx.block >= at_height {Some(wtx.txid.clone())} else {None})
                 .collect::<HashSet<TxId>>();
@@ -1716,7 +1740,10 @@ pub fn scan_full_mempool_tx(&self, tx: &Transaction, height: i32, _datetime: u64
         // Of the notes that still remain, unroll the witness.
         // Remove `num_invalidated` items from the witness
         {
-            let mut txs = self.txs.write().unwrap();
+            let mut txs = match self.txs.write() {
+                Ok(t) => t,
+                Err(p) => p.into_inner(),
+            };
 
             // Trim all witnesses for the invalidated blocks
             for tx in txs.values_mut() {